London digital switchover begins on Wednesday
BBC Two will be the first analogue channel in London to be switched off on Wednesday.
Digital UK said it believed thousands of analogue TV sets in the area needed to be converted to receive digital.
Freeview viewers also need to retune their TVs at the switchover or they will lose BBC One, BBC Two, BBC Three and BBC News.
Analogue BBC Two will disappear in London and parts of Berkshire, Essex, Hertfordshire, Kent, and Surrey.
The remaining analogue channels - BBC One, ITV1, Channel Four and Channel Five - will be turned off on 18 April.
The switchover comes 75 years after the first regular TV service began in London.
An estimated 12 million viewers will be affected in the London area, but a majority of homes have already switched to digital.